The present invention relates to a voltage (reference voltage: Vref) that is referred to when a semiconductor device (a memory or the like) used in an information processing device determines a logical value (0 or 1, or the like) in a wiring technique in a module, and in particular to a technique effectively applied in a wiring system for distributing the reference voltage at a low noise level.
For example, semiconductor devices used in an information or data processing device include a device (for example, a DRAM: Dynamic Random Access Memory or the like) which is externally supplied with a reference voltage (Vref) to determine a logical value based upon the voltage. That is, in a binary logic, an input voltage equal to or larger than the fixed voltage (Vref plus a defined voltage) is read as a logical value 1, while the input voltage smaller than the fixed voltage (Vref minus a defined voltage) is read as a logical value 0.
In recent years, according to speed-up of a signal processed in a semiconductor device, such a problem that a malfunction occurs in the semiconductor device due to a logical defect caused by convolution of noises to the Vref is being actualized. Considering types of noises in a memory module as one example, there are three types of noises, i.e., (1) propagation noise from an external system board, (2) noise generated by a memory itself, and (3) propagation noise from another memory on a module base board.
Approaches for reducing all the noises are required for a high-speed semiconductor. As one of the approaches, there is a method using a low pass filter (LPF) disclosed in Patent Document 1 (U.S. Pat. No. 6,646,945). This method is constituted such that the LPF is provided between a system board and a memory module so that noise propagation between the both is cut. The method is effective for reducing the noise (1). The noises (2) and (3) are reduced by a known technique. The known technique is classified to two categories. One is a plane feeding system and the other is a wire feeding system.